Why the gas line is the first question
A tankless heater fires at a much higher burn rate than a tank, because it has to heat a flowing stream in seconds. Many houses have a gas line sized for a tank, a furnace and a range, and adding a tankless unit may require a larger line or a new run from the meter.
The plumber adds up the gas load of every appliance and checks the pipe size and length. If the line is too small, flow drops when two appliances run, and the heater can shut down or deliver cold water.
What a tankless install adds to the job
| Item | Why it matters |
|---|---|
| Gas line sizing | Prevents fuel starvation when other appliances run |
| Venting | High efficiency units use plastic vent pipe and need a clear exit route |
| Condensate drain | Condensing units make acidic water that must drain away |
| Electrical outlet | Even gas units need power for the fan and controls |
| Water supply and isolation valves | Allow yearly flushing without cutting pipes |
| Freeze protection | Exterior walls and garages need heat or insulation |
Want to know if tankless fits your house?
Call and the plumber will walk through your gas line, venting path and location, then give a clear price.
Winter in the Treasure Valley
NOAA normals for the nearby Nampa station show a January average low near 23 degrees F and about 132 days a year at or below freezing. A tankless heater on an exterior wall or in an unheated garage has to be protected from the cold, since the fan, condensate line and exposed pipes can all freeze.
Many models have built-in freeze protection, but it only works with power to the unit. The plumber will choose a location, insulate the lines and explain what to do during a power outage in a freeze.
Caldwell rebates, permits and gas safety
Some Idaho gas utilities offer rebates on high efficiency tankless units. For example, Intermountain Gas Company's residential tankless rebate requires a minimum 0.91 UEF and an application within 90 days of installation. Ask your own gas provider whether a program applies to your address, because we do not name a provider for Caldwell homes.
Idaho says a permit is required when plumbing work is performed, and the City of Caldwell Building Safety Division takes plumbing permit applications online. Gas appliance work is inspected, and the plumber arranges the visit.
Gas and vent work for a tankless unit follows the 2015 Uniform Plumbing Code (UPC) with Idaho amendments.
Source: Intermountain Gas Company rebate page, Idaho DOPL Plumbing Bureau FAQ and the City of Caldwell Building Safety Division
Hard water, flushing and upkeep
Minerals form scale inside a tankless heat exchanger, so the unit needs to be flushed about once a year. Published Caldwell water reports do not always list hardness, so test your tap or ask the water department at 208-455-3070 before deciding on a softener.
Isolation valves make the yearly flush a short job. If your water is hard enough to need treatment, see water softener installation.
Signs a tankless heater is a good fit
A large family or heavy morning use
A tank can run out, and a tankless unit does not.
A tank in a tight closet
A wall mounted unit frees up floor space.
A tank near the end of its life
The replacement choice is open, so compare options.
A gas line that can be upsized
The biggest hurdle is already cleared.
Willingness to flush yearly
Upkeep is part of the deal.
A spot with a clear vent path
Short vent runs keep the install simple.
Questions to ask the installer
- What size gas line does this unit need, and does mine meet it?
- Where will the vent exit, and how long is the run?
- How is the condensate handled, and where does it drain?
- What freeze protection does the location need?
- Will the quote include isolation valves for yearly flushing?
A realistic picture of install day
A tankless swap usually takes longer than a tank swap because of the gas line, the vent and the wall mounting. Expect the plumber to be on site most of a day, with the water and gas off for part of it.
Once the unit is running, the plumber should walk you through the control panel, the error codes and the flushing valves. Ask for the manual and the model number in writing, since you will need them for warranty and service.
What to do if you smell gas
Leave the building at once. Do not use switches, plugs or a phone inside, then call 911 and your gas utility from outside.
After the utility says it is safe, a licensed plumber can find the leak and repair the connection. For a heater that has failed, see water heater repair.
Questions Caldwell homeowners ask
Often the existing line is too small for the higher burn rate. The plumber sizes the line by adding up every appliance on it.
Rebates come from gas utilities, not from the city. Check with your own gas provider, and note that one Idaho program requires a minimum 0.91 UEF and an application within 90 days of installation.
Gas tankless units need electricity for the fan and controls, so they stop when the power fails. A small backup battery can run some models for a short time.
About once a year, and more often in hard water. Test your tap if you are not sure how hard it is.
Yes with protection. Winters average about 132 days a year at or below freezing, so the unit needs freeze protection, insulation on lines and a power supply that stays on.
Yes. See the page for Middleton and the service areas for the towns covered.